KarlKnechtel: The throw-in is key here.
If White secures the eye in the corner first, Black ataris twice to prevent the second eye. at
doesn't work either, because of snapback.
If White captures first, Black makes the second eye in the centre false, also threatening to take away the other central eye. Now a and b are miai for the kill.
If White secures the central eye with (she cannot play at a due to shortage of liberties), Black removes the corner eye directly.